In recent years much effort has been aimed at the development of resonant cavity light emitting devices used as light sources, in the field of optical transmissions within a communications network. One such device is a Resonant Cavity Light Emitting Diode (RCLED). European Patent Application Publication No. EP 1 734 591 describes an RCLED having an electro-luminescent active layer placed between two mirrors made with a succession of layers of silicon dioxide and of silicon. The active layer constitutes the resonant cavity. The last layer of the lower mirror and the first layer of the upper mirror are made from doped silicon so as to constitute two electrically conductive layers. Such layers operatively constitute two armatures used to supply a pumping electrical signal to the cavity between which the electric field necessary for the generation of the radiation is established. Such electrically conductive layers are entirely included within the mirrors, lower and upper respectively.
It should be observed that the materials for making the mirrors are restricted by the fact that the last layer of the lower mirror and the first layer of the upper mirror must be made from silicon in order to be able to constitute the two armatures.
It should also be noted that the threshold voltage and the working voltage of such a device are quite high, typically around values of 25-30 V (threshold voltage) and 150-200 V (working voltage).